RESUMO
Renewable energy resources, which are becoming integrated into electric power systems around the world, connect to existing transmission grids at a range of voltage levels. The changes brought about by these new power sources are certain to have a significant impact on system performance and efficiency and to necessitate advances in the planning and operation of electric grids. Certainly there are challenges in developing renewable generation technologies, such as reducing the capital costs and improving energy efficiencies of the various types of renewable resources, such as wind, solar PV, solar thermal, and wave. Breakthroughs are also needed in large-scale energy storage technologies. To seamlessly integrate renewable resources in the grid research and development must address challenges that high penetration levels will have in power system planning and operation, and in grid connection. Finally, the existing workforce and the students going into power and energy engineering careers need to be educated so that they can envision and develop the new approaches and technologies to maintain grid reliability and economy. The challenges of integrating high penetrations of renewable energy technologies into the grid are less well recognized in part because they require interdisciplinary research in such areas as power systems analysis, communications, power electronics, economics, operations research, and industrial organization.